text: It was produced industrially from paraformaldehyde and a mixture of chlorosulfonic acid and sulfuric acid. It is also produced as a byproduct in the Blanc chloromethylation reaction, formed when formaldehyde (the monomer, paraformaldehyde or formalin) and concentrated hydrochloric acid are mixed, and is a known impurity in technical grade chloromethyl methyl ether.
  Because of their carcinogenic potency, the industrial production of chloromethyl ethers ended in most countries in the early 1980s. Bis(chloromethyl) ether was no exception to this with production in the U.S.A. ending in 1982.